Yes, and? What about Kansas/Nebraska?
Was not California admitted as a Free State in contravention to the Missouri Compromise?
Did either Kansas or Nebraska become slave states?
The Missouri Compromise did not require new states to be slave states below the Compromise line. It simply permitted it if the state wanted it. The people of California decided they did not want slavery and The Compromise of 1850, among other things, admitted California as a free state.
Not for lack of trying. You may have heard of Bleeding Kansas, Osawatomie Brown, the Lecompton Constitution and the Sack of Lawrence.
Proslavery Missouri senator David Atchison declared that “there are 1,100 men coming over from Platte County to vote, and if that ain’t enough we can send 5,000—enough to kill every Goddamned abolitionist in the Territory.”